The idea is a 5-10% fatal virus would have far more severe social distancing and thus couldn't infect everyone. Otherwise, a "100% fatal, infects everyone" disease would be the worst case scenario.
I wish I believed you, but sadly I think we learned nothing from COVID and if version 2.0 happens and is 5-10% fatal, we would make the same mistakes all over again: ignore it, downplay it, politicize it, and then finally half-ass the fight with the same weak uncoordinated actions.
The problem with COVID was that 70% of the deaths were in the 65+ range. So it didn't feel as severe to society as it would going by the death rate alone. We lost 3 years of life expectancy (it’s not clear if it will be recovered quickly or not), most people don’t think ahead that far so the problem feels abstract.